The main objective of this project was to assess whether the levels of tin, that are potentially added to food through preparation and storage, are sufficient to affect the utilization of essential nutrients. A 40-day human metabolic study was conducted with eight adult males. The control and test diets were identical, except the test diet contained 50 mg additional tin daily. Diet, fecal, and urine samples are now being analyzed for their tin, zinc, iron, and copper content. The tin content of more than 50 different foods were determined before the human metabolic study so that estimates of the usual tin intake of Americans could be made. The tin content of fresh, frozen, and bottled foods were found to be generally less than 0.1 microgram/g, while the tin content of canned foods were found to vary from less than 0.1 microgram/g to more than 150 microgram/g. In a preliminary study, rats fed a test diet which contained 206 microgram tin/g diet apparently absorbed significantly less zinc and copper than rats fed a control diet which contained 1 microgram tin 1 g diet. Test rats also had lower levels of zinc and copper in their kidneys and tibias than control rats.